//用两个栈实现一个队列。队列的声明如下，请实现它的两个函数 appendTail 和 deleteHead ，分别完成在队列尾部插入整数和在队列头部删除整数的
//功能。(若队列中没有元素，deleteHead 操作返回 -1 ) 
//
// 
//
// 示例 1： 
//
// 输入：
//["CQueue","appendTail","deleteHead","deleteHead"]
//[[],[3],[],[]]
//输出：[null,null,3,-1]
// 
//
// 示例 2： 
//
// 输入：
//["CQueue","deleteHead","appendTail","appendTail","deleteHead","deleteHead"]
//[[],[],[5],[2],[],[]]
//输出：[null,-1,null,null,5,2]
// 
//
// 提示： 
//
// 
// 1 <= values <= 10000 
// 最多会对 appendTail、deleteHead 进行 10000 次调用 
// 
// Related Topics 栈 设计 
// 👍 105 👎 0


package com.yun.leetcode.editor.cn;

import java.util.Stack;

public class YongLiangGeZhanShiXianDuiLieLcof {
    public static void main(String[] args) {
//        Solution solution = new YongLiangGeZhanShiXianDuiLieLcof().new Solution();
    }

    //leetcode submit region begin(Prohibit modification and deletion)
    class CQueue {
        private Stack<Integer> stack1;
        private Stack<Integer> stack2;

        public CQueue() {
            stack1 = new Stack<>();
            stack2 = new Stack<>();
        }

        public void appendTail(int value) {

            stack1.push(value);
        }

        public int deleteHead() {
            // stack2中有元素的话，stack2栈顶的元素算是尾部的，stack2中空的话，去stack1从去搂过来
//            while (!stack2.isEmpty()) {
//                stack1.push(stack2.pop());
//            }
//            if (stack1.isEmpty()) {
//                return -1;
//            }
//            while (stack1.size() != 1) {
//                stack2.push(stack1.pop());
//            }
//            return stack1.pop();

            if (!stack2.empty()) {
                return stack2.pop();
            }
            while (!stack1.isEmpty()) {
                stack2.push(stack1.pop());
            }
            if (stack2.isEmpty()) {
                return -1;
            } else {
                return stack2.pop();
            }
        }
    }

/**
 * Your CQueue object will be instantiated and called as such:
 * CQueue obj = new CQueue();
 * obj.appendTail(value);
 * int param_2 = obj.deleteHead();
 */
//leetcode submit region end(Prohibit modification and deletion)

}